Horizontal space between table and text

Question

In this code

\documentclass[11pt]{article}

\usepackage{amsmath}
\usepackage[ngerman]{babel}
\usepackage{siunitx}
\usepackage[a4paper,margin=2cm]{geometry}
\usepackage{graphicx}
\usepackage{lastpage}
\usepackage{xltabular,array}
\usepackage{showframe}

\sisetup{per-mode=fraction}

\pagestyle{empty}

\begin{document}
    
    \vspace*{-2cm}
    
    \noindent % it doesn't seem to make a difference
    
    \begin{tabular}{|>{\raggedright\arraybackslash}m{3cm}|>{\raggedright\arraybackslash}m{7cm}|>{\raggedright\arraybackslash}m{5cm}|>{\raggedright\arraybackslash}m{2cm}|}
        \hline
        %\rule[-1ex]{0pt}{0.5ex}
        \includegraphics[width=3cm]{example-image} & 
        \multicolumn{2}{|>{\raggedright\arraybackslash}m{12cm}|}{\rule[-1ex]{0pt}{4.5ex}{\LARGE \textbf{Mein-wunderschönes-Gymnasium}}} & \\
        &
        \multicolumn{2}{|>{\raggedright\arraybackslash}m{12cm}|}{{\rule[-2ex]{0pt}{6.5ex} \textbf{\Large Aufbau eines Versuchsprotokolls}}}  &
        \rule[-2ex]{0pt}{6.5ex} {\Large \textbf{(WHO)}}  \\
        \rule[-1ex]{0pt}{7.5ex} {\Large Klasse:} &
        \rule[-1ex]{0pt}{7.5ex} {\Large Name:}  &
        \rule[-1ex]{0pt}{7.5ex} {\Large Datum:}  &
        \rule[-1ex]{0pt}{7.5ex} {\Large Seite \thepage\ von \pageref{LastPage}} \\
        \hline
    \end{tabular}

    \section*{Section title begins here}
    
    Text begins here.
        
\end{document}

I get a table that doesn't start flush left at the text margin. I added the frame to show what I mean. I get

I know I could pull the table to the left with a \hspace, but that would require trial and error. Is there a length I need to adjust to fix this automatically? (Nevermind that the table is also too wide: I will fix that as soon as I got it aligned properly).

Answer 1

Do you need a table at all?

\documentclass[11pt]{article}

\usepackage[a4paper,margin=2cm]{geometry}
\usepackage{graphicx}
\usepackage{lastpage}
%\usepackage{showframe}

\pagestyle{empty}

\begin{document}

\vspace*{-2cm}
\noindent\begin{minipage}{\textwidth}
\hrule\smallskip

\LARGE

\makebox[0pt][l]{%
  \begin{tabular}{@{}c@{}}\includegraphics[width=3cm]{example-image}\end{tabular}%
}\hfill
\textbf{Mein-wunderschönes-Gymnasium}\hspace*{\fill}

\Large

\hspace*{\fill}\textbf{Aufbau eines Versuchsprotokolls\hspace*{\fill}\makebox[0pt][r]{(WHO)}}

\bigskip

\makebox[0.2\textwidth][l]{Klasse:}%
\makebox[0.4\textwidth][l]{Name:}%
\makebox[0.2\textwidth][l]{Datum:}\hfill
\begin{tabular}{@{}l@{}}Seite \thepage\ \\ von \pageref{LastPage}\end{tabular}

\smallskip
\hrule
\end{minipage}

\section*{Section title begins here}
    
Text begins here.
        
\end{document}

Without showframe

You can even have the header larger than the text width:

\documentclass[11pt]{article}

\usepackage[a4paper,margin=2cm]{geometry}
\usepackage{graphicx}
\usepackage{lastpage}
%\usepackage{showframe}

\pagestyle{empty}

\begin{document}

\vspace*{-2cm}
\noindent\hspace{-1cm}\begin{minipage}{\dimexpr\textwidth+2cm}
\hrule\smallskip

\LARGE

\makebox[0pt][l]{%
  \begin{tabular}{@{}c@{}}\includegraphics[width=3cm]{example-image}\end{tabular}%
}\hfill
\textbf{Mein-wunderschönes-Gymnasium}\hspace*{\fill}

\Large

\hspace*{\fill}\textbf{Aufbau eines Versuchsprotokolls\hspace*{\fill}\makebox[0pt][r]{(WHO)}}

\bigskip

\makebox[0.2\textwidth][l]{Klasse:}%
\makebox[0.4\textwidth][l]{Name:}%
\makebox[0.2\textwidth][l]{Datum:}\hfill
\begin{tabular}{@{}l@{}}Seite \thepage\ \\ von \pageref{LastPage}\end{tabular}

\smallskip
\hrule
\end{minipage}\hspace*{-1cm}

\section*{Section title begins here}
    
Text begins here.
        
\end{document}

Answer 2

In addition to eliminating the blank line after \noindent, you may want to (a) make sure that the table actually fits inside the textblock and (b) declutter the code, possibly along the following lines.

\documentclass[11pt]{article}
\usepackage[a4paper,margin=2cm]{geometry}
\usepackage{amsmath}
\usepackage[ngerman]{babel}
\usepackage{siunitx}
\usepackage{graphicx,lastpage,xltabular,array,calc}
\newcolumntype{M}[1]{>{\raggedright\arraybackslash}m{#1}}
%\usepackage{showframe}

\sisetup{per-mode=fraction}

\pagestyle{empty}

\begin{document}

\noindent % it makes a huge difference...
\begin{tabular}{@{}
   M{3cm}
   M{7cm-2\tabcolsep}
   M{4.75cm-2\tabcolsep}
   M{2.25cm-2\tabcolsep} @{}}
   \hline
   %\rule[-1ex]{0pt}{0.5ex}
   \includegraphics[width=3cm-\tabcolsep]{example-image} & 
   \multicolumn{2}{c}{\LARGE\textbf{Mein wunderschönes Gymnasium}} & \\
   &
   \multicolumn{2}{c}{\rule[-2ex]{0pt}{6.5ex}\Large\textbf{Aufbau eines Versuchsprotokolls}}  &
   \Large \textbf{(WHO)}  \\
        \rule[-1ex]{0pt}{7.5ex}\Large Klasse: &
        \rule[-1ex]{0pt}{7.5ex}\Large Name:  &
        \rule[-1ex]{0pt}{7.5ex}\Large Datum:  &
        \rule[-1ex]{0pt}{7.5ex}\Large Seite \thepage\ von \pageref{LastPage} \\
\hline
\end{tabular}

\section*{Section title begins here}
    
Text begins here.
        
\end{document}